Pilot interface for aircraft autothrottle control

ABSTRACT

An autothrottle for an aircraft that includes a power-control input (PCL) manually movable by a pilot along a travel path to effect a throttle setting that controls engine power of the aircraft. The autothrottle determines a control-target setting for a throttle of the aircraft and dynamically adjusts the throttle according to the control-target setting, including moving the PCL to achieve the control-target setting. A virtual detent is set and dynamically adjusted at positions along a travel path of the PCL corresponding to the control-target setting. The virtual detent is operative, at least when the autothrottle is in a disengaged state for autothrottle control, to indicate the control-target setting to the pilot via a haptic effect that applies a detent force opposing motion of the PCL in response to the PCL achieving the position of the virtual detent.

PRIOR APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/675,534 which was filed with the U.S. Patent and Trademark Office onFeb. 18, 2022 and which claims the benefit of U.S. ProvisionalApplication No. 63/150,788, filed Feb. 18, 2021, and U.S. ProvisionalApplication No. 63/167,424, filed Mar. 29, 2021, the disclosures ofwhich are all incorporated by reference herein.

TECHNICAL FIELD

The invention relates generally to aeronautics and aircraft control and,more particularly, to automatic throttle control for reducing pilotworkload and maintaining safe flight characteristics.

BACKGROUND

Automatic throttle systems for aircraft, commonly referred to asautothrottles, are systems that control an aircraft's engines withminimal pilot intervention. Such autothrottles provide the ability torealize truly automated, hands-off control of the aircraft, thusproviding increased aircraft operating efficiencies, reducing cost in,for example, the consumption of fuel, and vastly decreasing pilotworkload and thereby notably increasing flight safety. Autothrottles areubiquitous on large or sophisticated high-end aircraft, such as airlinepassenger jets, advanced regional and general aviation jets, andadvanced turbine-propeller airplanes, which generally incorporate anautothrottle as part of a comprehensive flight management system (FMS).The FMS also provides autopilot control with lateral navigation (LNAV)and vertical navigation (VNAV), which may control the aircraft along itsflight plan and maintain its operation within a safety envelope. FMS'sare comprehensive systems that are fundamentally integrated into theaircraft by the aircraft's manufacturer, and comprise a variety ofsensors and actuators throughout the aircraft to assess the aircraft'sconfiguration, position, orientation, speed, altitude, and performance,among other monitored parameters.

Due to the complexity and cost of FMS's, such systems have traditionallybeen considered impractical for smaller aircraft, such as those used forgeneral aviation. Small aircraft may include aircraft with single ormultiple engines using pistons or turbines (e.g., light aircraft or verylight jet (VU)), and which generally accommodate 10 or fewer passengers.Typically small aircraft have a maximum takeoff weight (MTOW) of under15,000 pounds (6,800 kg). Although small aircraft may include disparatesystems such as an autopilot, GPS-based navigation, and others, suchsystems tend to be offered as options by aircraft manufacturers, orretrofitted to an existing aircraft, and hence are generally notintegrated into a complete FMS. Also, certain sensors used by an FMS,such as a radar-based altimeter, redundant airspeed sensors, and thelike, are typically absent from small aircraft, further complicating theaddition of an FMS.

Likewise, autothrottle systems have traditionally been implemented inonly large or technologically-advanced aircraft (e.g., which have FMS's)because traditional autothrottle systems generally require physical,spatial, and other accommodations are not available on small aircraft.In most aircraft, the throttle(s)—which are selectively adjustable tocause the engine(s) to generate a predetermined amount of power orthrust—are adjusted by pilot-controlled manual override displacement ofone or more graspable handles on levers that are commonly mounted in theaircraft cockpit or flight control deck and movable along a linear or anarcuate path. These levers are operatively coupled to the engines orengine controller(s).

In almost any aircraft, not insignificant forces must be applied to thethrottle levers-whether manually by a pilot or by an operating motor ofan autothrottle system—to vary or adjust the positions of the levers.The motors of the system, therefore, must be fairly robust, both in sizeand weight (to provide sufficient torque and operating forces applied tothe power control lever(s) (PCL)) and in construction (to assurecontinued reliability through tens of thousands of activations andoperations). As a consequence, only aircraft specifically designed andconstructed with sufficient clearances and space to accommodate suchmotors and associated elements at, in, or alongside the throttles withinthe cockpit, and capable of accepting the significant additional weightassociated with these systems and their component parts, are able toincorporate such autothrottles into and with their flight controls.Traditionally, there has been no ability to retrofit or add autothrottlecapabilities into existing aircraft that have not already been speciallydesigned and constructed to accommodate the associated operatingcomponents of an autothrottle system.

U.S. Pat. No. 11,027,854 to Hedrick, entitled “Precision Operator for anAircraft Autothrottle or Autopilot System with Engine PerformanceAdjust,” the disclosure of which is incorporated by reference herein,describes an autothrottle system that is compact, lightweight, reliableand readily installable in an aircraft, even in small aircraft withoutany special accommodation for adding or providing conventionalautopilot/autothrottle capabilities. The autothrottle system includes amotor that is mechanically coupled to the aircraft's PCL via aclutchless interconnect that allows the motor to move the PCL inresponse to commands issued by an autothrottle controller when theautothrottle system is engaged, while also allowing the pilot tomanually overpower the motor-driven motion of the PCL without firstdisengaging the autothrottle.

Although the technology described in the Hedrick patent, or in othersuch technology relating to autothrottle systems for small aircraft, mayprovide important and practical solutions to a number of challengespreviously encountered in implementing autothrottles, there remains aneed to further improve the pilot interface with the autothrottle systemto make its operation more intuitive, simple, and safe. This needbecomes increasingly pressing considering the ongoing advancements inthe functionality of autothrottle systems.

SUMMARY OF THE DISCLOSURE

One aspect of this disclosure is directed to a system for controlling anautothrottle of an aircraft that includes, a power-control input (PCL)manually movable by a pilot along a travel path to effect a throttlesetting that controls engine power of the aircraft. The system includesan autothrottle controller including processing circuitry, memory, andinput/output facilities, with the autothrottle controller beingoperative to execute instructions including a user-interface process andan autothrottle control program. An autothrottle actuator ismechanically coupled to the PCL and is operative to set and dynamicallyadjust the PCL in response to an output of the autothrottle controller.The autothrottle control program, when executed, causes the autothrottlecontroller to determine a control-target setting and to command theautothrottle actuator to set and dynamically adjust the PCL according tothe control-target setting when the system is in an engaged state forautothrottle control. The user-interface process, when executed, causesthe autothrottle controller to set and dynamically adjust a virtualdetent, the virtual detent being located at a position along the travelpath of the PCL corresponding to the control-target setting. The virtualdetent is operative, at least when the system is in a disengaged statefor autothrottle control, to indicate the control-target setting to thepilot via a haptic effect that applies a detent force opposing motion ofthe PCL in response to the PCL achieving the position of the virtualdetent.

Another aspect is directed to a system for controlling an autothrottleof an aircraft, the system comprising an autothrottle controller that isoperative to execute instructions including a user-interface process andan autothrottle control program. An autothrottle actuator sets anddynamically adjusts a throttle setting that controls engine power of theaircraft in response to an output of the autothrottle controller. Anautothrottle activation input device, an autothrottle mode input device,and a display device are all operatively coupled to the autothrottlecontroller. The autothrottle control program, when executed, causes theautothrottle controller to determine a control-target setting and tocommand the autothrottle actuator to set and dynamically adjust thethrottle setting according to the control-target setting when the systemis in an engaged state for autothrottle control. The user-interfaceprocess, when executed, causes the autothrottle controller to respond toactuation of the autothrottle activation input device by togglingbetween the engaged and the disengaged states; respond to actuation ofthe autothrottle mode input device by switching between different onesof a plurality of autothrottle control modes; and display informationindicative of a selected one of the plurality of autothrottle controlmodes on the display device.

A further aspect is directed to an autothrottle system with anautothrottle controller operative to execute instructions including anautothrottle control program, and an autothrottle actuator to set anddynamically adjust a throttle setting that controls engine power of theaircraft in response to an output of the autothrottle controller. Theautothrottle control program, when executed, causes the autothrottlecontroller to command the autothrottle actuator to set and dynamicallyadjust the throttle setting according to different ones of a pluralityof autothrottle control modes, where each of the autothrottle controlmodes defines a corresponding control-target setting. Further, theprogram causes the autothrottle to autonomously transition from one ofthe autothrottle control modes to another one of the autothrottlecontrol modes in response to a determination by the autothrottlecontroller that mode-transition criteria has been met.

A method according to a related aspect of this disclosure is forcontrolling an autothrottle of an aircraft that includes, a PCL. Themethod includes: determining, by an autothrottle controller acontrol-target setting for a throttle of the aircraft; dynamicallyadjusting the throttle according to the control-target setting,including moving the PCL to achieve the control-target setting when theautothrottle is in an engaged state for autothrottle control; andsetting and dynamically adjusting a virtual detent, the virtual detentbeing located at a position along a travel path of the PCL correspondingto the control-target setting, wherein the virtual detent is operative,at least when the autothrottle is in a disengaged state for autothrottlecontrol, to indicate the control-target setting to the pilot via ahaptic effect that applies a detent force opposing motion of the PCL inresponse to the PCL achieving the position of the virtual detent.

In another method as described herein, an autothrottle controllerperforms the following operations: determining a control-target settingfor a throttle of the aircraft; dynamically adjusting the throttleaccording to the control-target setting when the autothrottle is in anengaged state for autothrottle control; and reading input from anautothrottle activation input device; reading input from an autothrottlemode input device; responding to actuation of the autothrottleactivation input device by toggling between the engaged and thedisengaged states; and responding to actuation of the autothrottle modeinput device by switching between different ones of a plurality ofautothrottle control modes.

A further method for controlling an autothrottle of an aircraftincludes: autonomously, dynamically adjusting a throttle settingaccording to different ones of a plurality of autothrottle controlmodes, where each of the autothrottle control modes defines acorresponding control-target setting; and autonomously transitioningfrom one of the autothrottle control modes to another one of theautothrottle control modes in response to a determination thatmode-transition criteria has been met.

Related aspects of the subject matter include instructions (stored on atleast one tangible, non-transitory machine-readable medium) that areexecutable on a controller of an autothrottle system to perform theoperations according to any of the methods described herein.

A number of advantages will become apparent from the following DetailedDescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings.

FIG. 1 is a simplified diagram illustrating an aircraft and basic forcesinvolved in its flight.

FIG. 2 is a diagram illustrating a cockpit or flight deck of anaircraft, in which autothrottle controls are implemented in accordancewith some embodiments of this disclosure.

FIG. 3 is a block diagram illustrating an autothrottle control systemaccording to some embodiments.

FIG. 4 is a simplified block diagram illustrating components ofautothrottle controller according to an example implementation.

FIG. 5 is a simplified block diagram illustrating portions of certaininstructions executable by the autothrottle controller according to someexamples.

FIG. 6 is a state diagram illustrating some basic states of anautothrottle control system according to some embodiments.

FIG. 7 is a diagram illustrating examples of virtual detent force atvarious positions along the travel path of a power control lever (PCL)according to some embodiments.

FIGS. 8A-8B illustrate another example of a virtual detent which iscomposed of a combination of oppositely-directed forces applied by theautothrottle system, according to additional embodiments.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

It should be noted that aspects of this disclosure are applicable in anypowered aircraft, including traditional fuel-burning aircraft(propeller-driven, turboprop, jet, or other), electric aircraft(battery-, solar-, or fuel cell-powered), or hybrid-powered aircraft. Inthe following description, various embodiments are described in thecontext of one, or some, types of propulsion orpropulsion-energy-delivery systems; however, it should be understoodthat principles of the described embodiments may be suitably applied toother types of aircraft having other propulsion orpropulsion-energy-delivery systems with suitable adaptation which iswithin the skill of aircraft technologists.

FIG. 1 is a simplified diagram illustrating aircraft 100 and basicforces involved in its flight. Aircraft 100 generates lift 102 from itsforward motion by directing air downward using primarily the shape andorientation of the body of aircraft 100 (e.g., its wings, fuselage, andcontrol surfaces). Lift also depends on the density of the air, thesquare of the velocity, the air's viscosity and compressibility, thesurface area over which the air flows. The dependence on body shape ofaircraft 100 is complex and difficult to model mathematically. Theeffect of inclination of aircraft 100, air viscosity (e.g., due to airtemperature, humidity, and altitude), and compressibility on the lift isvariable and also difficult to derive for a given operating condition.

Drag 104 is a force that resists the forward motion of aircraft 100.Drag 104 has a number of components, such as aerodynamic frictionbetween the air and the surface of aircraft 100 (skin friction),aerodynamic resistance to the motion of the aircraft 100 through the air(form drag), and drag caused by lift (induced drag), among others, whichare likewise difficult to account for in order to compute dragpredictively. Like lift 102, drag 104 depends on a number of complexfactors, including the size, shape, and weight of aircraft 100, thesurface properties of aircraft 100, fluid characteristics of the air,and other parameters. Notably, different parameters of drag 104 prevailat different airspeeds. At low airspeeds, a primary component of drag104 is the induced drag. As aircraft 100 increases its airspeed, lift102 is generated more easily, and the induced drag actually reduces.However, with increasing airspeed, the other drag components,collectively referred to as parasitic drag, increase.

Thrust 106 is the propulsion force generated by aircraft 100 to overcomedrag 104. Generation of thrust requires consumption of fuel or otheronboard energy source (e.g., electrical charge in the case ofbattery-powered aircraft). The magnitude of the thrust depends on anumber of parameters relating to the propulsion system of aircraft 100,such as the type and quantity of engines, and the throttle setting(s).Weight 108 is a combination of gravity and the mass of aircraft 100,including the mass of the airframe, plus the mass of the fuel (which isa time-varying quantity in the case of fuel-consuming aircraft), plusany payload on board aircraft 100 (people, freight, etc., which may alsobe dynamically-varying as in the case of air-dropping operations). Thedynamic variability of weight 108 means that the amounts of lift 102 anddrag 104 also vary over time during the flight of aircraft 100.

The performance of aircraft 100 is limited by various physicalconstraints. For instance, the airspeed is practically limited by theaerodynamics and structural strength of the airframe of aircraft 100, aswell as by the available thrust. Also, there are limits to the power,thrust, or torque that the engine(s), shaft(s), propellers, and otherassociated components can withstand. Likewise, the engine(s) are limitedby the temperature at which the engine components or fluids may beoperated. Such various constraints and are typically represented asmaximum ratings provided by the engine manufacturer.

During the operation of aircraft 100, different constraints dominate theaircraft's performance limitations depending on the phase of flight, airdensity and temperature, and other parameters. For instance, duringtakeoff and climb, the performance of aircraft 100 tends to be limitedprimarily by the maximum engine power, thrust, or torque, whereas duringcruise, the performance of aircraft 100 tends to be limited by enginetemperature.

Because of the complexity and variability of the forces of both, lift102 and drag 104, it is difficult for the pilot of aircraft 100 tomaintain the optimal throttle setting, accounting for the currentaltitude, weight, and conditions of the air, in order to take off,climb, or cruise at the desired operating point, which may be, forexample:

-   -   the point of maximum power, thrust, or torque in takeoff or        climb phases;    -   the point of maximum temperature during cruise; or    -   the point of maximum efficiency for maximum-endurance flight.

According to some embodiments, an autothrottle control system isemployed in an aircraft to dynamically determine a suitable PCL setting,which may correspond to a set operating point for the current phase offlight. The operating point may be set and varied by the pilot using aninterface of the autothrottle system that includes the PCL. Also, theoperating point may be automatically adjusted by the autothrottle systemto maintain a safe flight envelope.

In a related aspect, the interface of the autothrottle system utilizescertain specialized controlled behaviors of the PCL to effect a hapticindication. For instance, a virtual detent, or stopping point, of thePCL, as described in detail below, is implemented by the autothrottlesystem to indicate a PCL set point to the pilot.

In another related aspect, a simple set of input devices, such asswitches, pushbuttons, or the like, accompany the PCL to facilitatepilot control of the autothrottle, including an input to set theautothrottle control mode, and an input to set or change the virtualdetent position.

In some implementations, aspects of this disclosure may be implementedin conjunction with an autothrottle arrangement such as one shown anddescribed in U.S. Pat. No. 11,027,854, the disclosure of which isincorporated by reference herein, may be utilized. In otherimplementations, other suitable autothrottle arrangements may be used toimplement aspects of the present disclosure.

FIG. 2 is a diagram illustrating a cockpit or flight deck 200 (theseterms may be used interchangeably in the present context) of anaircraft, such as aircraft 100, in which autothrottle pilot-interfacecontrols are implemented in accordance with some embodiments of thisdisclosure. Cockpit 200 includes PCL 202 which, in this example, ispivotably mounted in the center console, and movable in the forward andaft directions along an arcuate travel path.

PCL 202 may be a single lever, as shown in the example illustrated, orit may comprise multiple levers (not shown) in the case of amulti-engine aircraft. For simplicity, this description will refer toone or more power-control levers simply as the “PCL,” unless specificreference to multiple levers is intended. In a more general embodiment,rather than a lever, a power-control input may be provided in adifferent form. For example, a power control input may be implemented asat least one slider, knob, wheel, pedal, or other pilot-actuatablemechanism (or set of mechanisms). Here, too, for the sake of brevity,the power-control input (in whichever form it may be) is referred tosimply as a “PCL.”

PCL 202 is coupled, via a suitable operative coupling arrangement, tothe respective engine(s) and fuel-delivery system(s) of aircraft 100.For example, the operative coupling arrangement may be a mechanicalsystem that regulates the engine power based on the positioning of therespective power-control lever(s). The engine power may be varied byvarying the flow of fuel or combustion air to the engine(s). In anotherexample, as in the case of a fly-by-wire arrangement, the operativecoupling may include an electrical system that carries command signalingfrom the PCL to an actuator that regulates the engine power (e.g., flowof fuel or combustion air or, in the case of electric aircraft, thedelivery of electrical power to the engine(s)) based on the settingsprovided into the PCL.

PCL 202 is also coupled to an autothrottle actuator (not shown). Theautothrottle actuator, and its coupling to PCL 202 may be implemented asdescribed in U.S. Pat. No. 11,027,854, or they may be implemented inother suitable ways. Notably, the autothrottle actuator is arranged tomove PCL 202 in accordance with the autothrottle control when theautothrottle system is engaged, while also permitting the pilot to movePCL 202 while the autothrottle system is engaged. The autothrottlesystem is further arranged to detect and monitor the position of PCL202, as described in U.S. Pat. No. 11,027,854, or by other suitablesensing means. Therefore, PCL 202 serves as a portion of theautothrottle pilot-interface controls.

The example depicted in FIG. 2 illustrates additional autothrottlepilot-interface controls, namely, autothrottle activation control 204,takeoff/go around control 206, and autothrottle mode selector 208. Thesecontrols 204-208 are implemented as momentary pushbutton switchesaccording to the embodiment depicted. However, in other embodiments,controls 204-208 may be implemented using other types of inputmechanisms, such as selector knob(s), rocker switches, multi-positionselector switch(es), toggle switch(es), push-on/push-off switch(es),soft-key controls (e.g., via touchscreen), or the like.

In addition, autothrottle mode display 210 is provided. Autothrottlemode display 210 may include LED or LCD segments, a matrix of LED or LCDdevices, or other suitable display technology, along withdisplay-decoder or driver circuitry, which interfaces the display devicewith an autothrottle controller (described below). In the exampledepicted, autothrottle mode display 210 is integral with autothrottlemode selector 208 such that information is displayed on the pilot-facingsurface of autothrottle mode selector 208. In other embodiments,autothrottle mode display 210 is separate from autothrottle modeselector 208, and may be placed elsewhere in the control panel ofcockpit 200. In still other embodiments, autothrottle mode display 210is implemented using a general-purpose information display present incockpit 200, such as an instrument display or navigation display screen,or as part of the information displayed on a heads-up display.

FIG. 3 is a block diagram illustrating an autothrottle control system300 according to some embodiments. As depicted, system 300 includesmanual throttle input 302, which may take the form of a PCL, such as PCL202, or other type.

Autothrottle actuator 304 is a parallel subsystem to manual throttleinput 302. Autothrottle actuator 304 automatically regulates the enginepower based on command signaling 305 that is generated by autothrottlecontroller 310. In one example, autothrottle actuator 304 comprises amotor and motor controller, such as a servo motor system, with the rotorof the motor mechanically coupled to manual throttle input 302. Inanother example, autothrottle actuator 304 is an actuator coupled to theengine(s) or fuel system of aircraft 100, and may include one or morevalves for controlling a flow rate of fuel of combustion air to theengine(s). In another example, autothrottle actuator 304 includes one ormore switches, transmission gates, or signal amplifiers interfaced withan engine control system of aircraft 100.

Manual throttle input 302 and the output of autothrottle actuator 304combine to produce throttle setting 306, which is provided as theengine-power input to the engine(s) and fuel system as applicable. Thecombination of manual throttle input 302 and the output of autothrottleactuator 304 may be achieved mechanically, electromechanically, orelectronically, according to various implementations.

In some embodiments, when autothrottle is engaged, autothrottle actuator304 controls throttle setting 306 in the absence of manual throttleinput 302; however, manual throttle input 302, when present, overridesautothrottle actuator 304 to control throttle setting 306. In otherembodiments, throttle setting 306 may implement a different combinationof manual throttle 302 and autothrottle 304 when both inputs aresupplied simultaneously. For instance, autothrottle actuator 304 may beprovided to throttle setting 306 as a relatively lower-weighted input,whereas manual throttle input 302 may be provided as a relativelyhigher-weighted input. In related implementations, a sufficient force isneeded at manual throttle input 302 to override autothrottle actuator304. In other related implementations, throttle setting 306 provides amechanical force or electronic signal as feedback 307 to manual throttleinput 302, such that the effect of autothrottle actuator 304 may be feltor otherwise observed by the pilot at manual throttle input 302.

Throttle setting sensor 308 is arranged to detect the state of throttlesetting 306, and provide signal 309 representing that detected state toautothrottle controller 310. Notably, signal 309 represents the effectof manual throttle input 302 on throttle setting 306 when manualthrottle input 302 is asserted. In some embodiments, throttle settingsensor 308 is not necessary and may be omitted, for instance, whenthrottle setting 306 is output as an electronic signal (in which casethrottle setting 306 may be fed directly to autothrottle controller310). Throttle setting sensor 308 may be utilized in embodiments wherethrottle setting 306 is realized as a mechanical force or motion (suchas movement or positioning of a power-control lever, or movement orpositioning of a throttle-control cable or associated linkage).

Autothrottle controller 310 produces command signaling 305 for thecontrol of autothrottle actuator 304 based on a plurality of inputs.Autothrottle mode input 312 is provided by the pilot of aircraft 100 viaautothrottle mode selector 208, and includes such parameters asengagement/disengagement of autothrottle controller 310, and selectionfrom one or more available autothrottle programs that define thebehavior or operational objective of the autothrottle.

Other inputs to autothrottle controller 310 may include autothrottleactivation input 314, and autothrottle TO-GA command input 316.Autothrottle activation input 314 is provided via autothrottleactivation control 204, and is operable by the pilot in various patterns(e.g., short press/long press) to select between engaged and armedstates of the autothrottle control, as well as to completely disengagethe autothrottle to a disarmed state. Autothrottle takeoff/go around(TO-GA) input is provided via takeoff/go around control 206, and isoperable by the pilot to place the autothrottle in a takeoffautothrottle program when aircraft 100 is on the ground, or to place theautothrottle in a climb (go-around) program when aircraft 100 is in theair. Additional functions may be assigned to inputs 312-316, which maybe actuated individually, or in combination with throttle input 302 viaPCL 202. For instance, autothrottle activation input 314 may be furtheractivated in a certain pattern (e.g., double-press) by the pilot totoggle between coarse or fine speed adjustment of the autothrottle.Likewise, actuation of autothrottle activation input 314 in conjunctionwith positioning of PCL 202 may be used by the pilot to set or re-set anautothrottle control-target setting.

Autothrottle controller 310 may also receive various inputs fromsensors, such as engine temperature sensor 320, engine torque sensor322, and airspeed sensor 324, along with other available sensors onaircraft 100, such as altimeter, fuel-consumption-rate sensor, etc.

FIG. 4 is a simplified block diagram illustrating components ofautothrottle controller 310 according to an example implementation.Autothrottle controller 310 includes central processing unit (CPU) 410,which may include one or more processor cores 412. Memory circuitry 414may include static or dynamic random-access memory (RAM) and a memorycontroller circuit interfaced with CPU 410. Instructions 416 may bestored on a read-only memory (ROM) device, or an electrically-erasableprogrammable read-only memory (EEPROM) device such as a flash EEPROMdevice interfaced with CPU 410 or the memory controller circuit ofmemory 414. Input/output (I/O) controller 418 includes interfaces to thevarious inputs and command signaling output 305 described above. In someimplementations, I/O controller 418 may include a universal asynchronousreceiver/transmitter (UART) for serial communications, a parallel port,analog-to-digital (A/D) converter, or a digital-to-analog converter(D/A). I/O controller 418 may be interfaced with CPU 410 or memorycontroller of memory 414.

Autothrottle controller 310 is operative to execute instructions 416 inorder to carry out the functionality of autothrottle control system 300.FIG. 5 is a simplified block diagram illustrating portions ofinstructions 416 according to some examples. In operating autothrottlecontrol system 300 via autothrottle mode input 312 or autothrottle TO-GAinput 316 the pilot of aircraft 100 may select from among certainavailable programs which dictate the control algorithm of theautothrottle operation. Also, the operating state of the autothrottle isselectable via autothrottle mode input 312 and autothrottle activationinput 314.

Instructions 416 include user-interface process 502, flight-safetyoversight process 504, airspeed program 510, engine-thrust program 512,maximize endurance program 514, maximize airspeed program 516, andtakeoff/go-around program 518. Each process or program comprises a setof instructions executable by autothrottle controller 310 for operatingautothrottle control system 300. In general, each of programs 510-518 isexecuted individually (although one program may automatically transitionto another program). However, user-interface process 502 andflight-safety oversight process 504 are continuously executed.

User-interface process 502 is operative to monitor all user inputs (and,optionally, certain sensors) and set the autothrottle control system 300into various states in response thereto. FIG. 6 is a state diagramillustrating some basic states, according to an example implementation.The basic states include disarmed state 602, and armed state 604. Armedstate 604 comprises engaged state 612, and disengaged state 614.Autothrottle control system 300 transitions from disarmed state 602 intoarmed-disengaged state 614 via transition 603, and transitions fromarmed-disengaged state 614 back to disarmed state 602 via transition615. Autothrottle control system 300 transitions from disarmed state 602into armed-engaged state 612 via transition 605, and transitions fromarmed-engaged state 612 back to disarmed state 602 via transition 613.In the armed state, autothrottle control system 300 transitions betweenengaged state 612 and disengaged state 614 via transitions 617 and 619,as shown.

In disarmed state 602, the autothrottle control system 300 is generallyinoperative. It may be completely inoperative in some embodiments or, inother embodiments, the autothrottle control system 300 may be minimallyoperative to monitor certain safety-related indicia, such asoverspeed/underspeed, overtemp, overtorque, and may autonomously engageautopilot control in response to an unsafe condition in order to restoreand maintain a safe flight envelope. In the armed states 604, theautothrottle control system 300 monitors the control inputs anddetermines the autothrottle control-target settings. In armed-disengagedstate 614, the autothrottle control system 300 does not normally actuatePCL 202 in accordance with the control-target settings, although virtualdetents may be set and adjusted. In armed-engaged state 612, theautothrottle control system 300 commands autothrottle actuator 304 toset and adjust PCL 202 in accordance with the control-target settings.

Table 1 below summarizes various operations of pilot inputs that arehandled by user-interface process 502, according to an exampleimplementation.

TABLE 1 CONTROL INPUT FUNCTIONALITY AUTOTHROTTLE Press and hold (>1 sec)to engage or disengage MODE SELECTOR the autothrottle. 208 Short pressto toggle between THR-SPD mode (when engaged); or THR armed-SPDarmed-OFF (when not engaged). AUTOTHROTTLE Press and hold (>1 sec) todisengage the ACTIVATION autothrottle completely. CONTROL 204 Shortpress to disconnect into the armed state, or re-engage from armed state.Double-press to toggle fine/coarse speed adjustment while armed.TAKEOFF/ Press to activate Takeoff mode (on ground), or GO AROUNDGo-Around mode (in air). CONTROL 206 PCL 202 Move to adjust theautothrottle control target (e.g., speed or torque) when theautothrottle is in the armed state.

In one embodiment, autothrottle mode selector 208 is a button that isused to initially arm the autothrottle system and toggle betweenautothrottle modes. The modes are described in greater detail below andmay include (without limitation):

TO - Takeoff mode CLB - Climb mode CRZ - Cruise - max power mode THR -Thrust-hold mode GA - Go-around mode ### - Set-speed control mode OFF -Disengaged

The mode selector 208 button, mounted on the instrument panel, mayincorporate display 210 (e.g., a backlit-LCD or LED array on the buttonface) to display autothrottle mode and speed target values. Autothrottlemodes may be displayed in a first color, e.g., white, when in thearmed-disengaged state 614, and in a second color, e.g., green, when inthe armed-engaged state 612.

Pressing the autothrottle mode selector 208 button while not in anyarmed state 604 arms the autothrottle. The autothrottle initially armsat the current torque or airspeed. Repeated presses of the autothrottlemode selector 208 button toggles between Thrust and Speed modes (Thrustarmed, Speed armed, and Off if not engaged). Pressing and holding theautothrottle mode selector 208 button (for >1 sec) engages or disengagesthe autothrottle. The autothrottle can only be engaged from an armedstate 604.

When the autothrottle system 300 is in an armed state 604, PCL 202 canbe moved to adjust the autothrottle target torque or speed value.

Autothrottle activation control 204, in one embodiment, is a button islocated on the right side of the PCL handle. Pressing the autothrottleactivation control 204 button will place the autothrottle system 300into armed-engaged state 612, or disconnect the autothrottle into thearmed-disengaged state 614. Pressing the autothrottle activation control204 button again will re-engage the (armed) autothrottle into state 612to actively maintain the updated torque or speed target. Double-pressingthe autothrottle activation control 204 button while in thearmed-disengaged state 614 in the speed-control mode will toggle coarseor fine adjustment of the target speed. Pressing and holding theautothrottle activation control 204 button (>1 sec) will disengage theautothrottle completely returning to disarmed state 602.

In one embodiment, takeoff/go around control 206 is implemented as abutton on the left side of the PCL handle. If the autothrottle system isin the armed-disengaged state 604 and the mode is set to Takeoff (TO)mode, activating the takeoff/go around control 206 button on thethrottle handle will activate TO mode and PCL 202 will automaticallyadvance to the maximum continuous thrust setting. When aircraft 100 isin the air, pressing the takeoff/go around control 206 button while theautothrottle is in either armed state 612, 614 will activate Go-Around(GO) mode and the PCL will automatically advance to maximum continuousthrust under the control of the autothrottle.

In some embodiments, behavior of the PCL is controlled in a specificmanner by user-interface process 502 to set one or morevariably-positionable virtual detents along the travel path of PCL 202.The virtual detents are thus implemented by autothrottle controller 310and autothrottle actuator 304 to indicate an autothrottle control-targetsetting to the pilot through a haptic effect using PCL 202. A virtualdetent may be effected by application of a force by autothrottleactuator 304 that opposes manual throttle input 302 at a set locationalong the travel path of PCL 202. The position of the virtual detentalong the travel path of PCL 202 is variable by autothrottle controller310. Likewise, the detent force may be variable by autothrottlecontroller 310. Multiple virtual detents of the same, or different,detent forces may be implemented at a given time along the travel pathof PCL 202. As described in greater detail below, the virtual detentsmay be automatically varied by other processes, such as flight-safetyoversight process 504, engine-thrust program 512, and others, to accountfor changes in operating conditions of aircraft 100. When a virtualdetent position is autonomously moved by autothrottle controller 310while the PCL is set at the virtual detent, the PCL 202 is moved to therevised detent position.

FIG. 7 is a diagram illustrating examples of virtual detent force atvarious positions along the travel path of the PCL. As depicted, a firstvirtual detent 702 is implemented as a force applied by the autothrottlesystem to oppose the motion of the PCL when the PCL is positioned at aportion along its travel path. A second virtual detent 704 is similarlyimplemented at another position. Notably, second virtual detent 704 hasa higher detent force than virtual detent 702, and is applied over agreater (wider) range of the travel path. First virtual detent 702 mayrepresent a virtual detent associated with a particular engine thrustsetting, whereas second detent 704 may represent a safety-based limit ofengine thrust.

FIGS. 8A-8B illustrate another example of a virtual detent 800A, 800Bwhich is composed of a combination of oppositely-directed forces appliedby the autothrottle system to provide the haptic sensation of the PCL“falling into” a detent. Virtual detent 800A, 800B is implemented byautothrottle actuator 304 under the control of autothrottle controller310, which also monitors the PCL position via throttle setting sensor308. As illustrated in FIG. 8A, virtual detent 800A is composed of twoopposite detent forces that are applied sequentially as the PCL is movedin first direction 802A along its travel path. Non-opposing detent force804A is oriented in the direction of travel (i.e., assisting themovement of the PCL along direction 802A), whereas detent force 806opposes any movement of the PCL. This combination of forces simulatesthe haptic sensation of a mechanical detent into which the PCL would bedrawn. FIG. 8B illustrates the virtual detent 800B, which achieves thesame PCL setting as virtual detent 800A, except that virtual detent 800Bis implemented as the PCL moves toward its location in the oppositedirection, 802B. As the PCL approaches the location of virtual detent800B, non-opposing detent force 804B is applied along the direction oftravel 802B, and then detent force 806 opposes the direction of travel.This example demonstrates that a virtual detent may be responsive to thedirection of manual movement of the PCL.

User-interface process 502 facilitates various pilot interactions withthe virtual detent(s). For instance, momentary actuation of autothrottleactivation control 204 while the autothrottle is in the armed-engagedstate 612 releases the virtual detent while transitioning the state tothe armed-disengaged state 614, thus allowing movement of PCL 202 to adifferent position (which may or may not itself be another virtualdetent). In a related embodiment, manual placement of PCL 202 at aposition of a virtual detent (while autothrottle system 300 is in thearmed-disengaged state 614) will cause the autothrottle to re-engageinto armed-engaged state 612 (provided that the selected modeaccommodates such engagement). As another provision by user-interfaceprocess 502, the pilot of aircraft 100 may set a new virtual detent byholding the autothrottle activation control 204 button while moving thePCL to a position that achieves the desired setting for torque,indicated air speed (IAS) or Mach number.

Turning again to FIG. 5 , flight-safety oversight process 504 isoperative to monitor the aircraft's sensors (e.g., engine temperaturesensor 320, engine torque sensor 322, airspeed sensor 324, altimeter,etc.) and compare the present state of operation or performance, or thecondition, of aircraft 100 to the predefined constraints of aircraft 100and its engine(s), to ensure that the aircraft is being operated withinits safe flight envelope. For instance, overspeed/underspeed at thepresent altitude, temperature limit, torque limit, differential torquein multi-engine aircraft, and the like, may be monitored, and theautothrottle system's controls may be overridden to adjust the PCLsetting so that the aircraft remains within safe operating conditions.

In related embodiments, flight-safety oversight process 504 may set orvary the position(s) of one or more virtual detents according tovariations in altitude, engine temperature, or other measuredconditions. For instance, if an engine temperature limit is beingapproached by the current measured temperature, a virtual detent may beadded or moved to indicate a limit to the pilot when the autopilotsystem 300 is in the armed-disengaged state. In a related example, thevirtual detent associated with a safety limit has a higher detent force(i.e., the force opposing pilot movement of the PCL) than anon-safety-related detent.

Airspeed program 510 causes the autothrottle to implement a basicfixed-airspeed control (set-speed control mode). Program 510 acceptspilot input to set a particular airspeed, which may be set via manualthrottle input 302. Thereafter, airspeed program 510 operatesautothrottle actuator 304 to increase engine power if the indicatedairspeed drops below the set point, and to decrease engine power if theindicated airspeed rises above the set point. When the autothrottle isengaged in a set-speed control mode, the pilot may press theautothrottle activation control 204 button to release the autothrottleinto armed-disengaged state 614 and move the throttle lever to select anew target speed (which may be displayed in white on display 210). Afterthe target speed is selected, pressing the autothrottle activationcontrol 204 button again re-activates the autothrottle to maintain theselected airspeed. In the armed-disengaged state 614, while in set-speedcontrol mode, movements of the throttle lever may be translated totarget speed changes rounded to 5-knot increments. Double-clicking theautothrottle activation control 204 button allows the target speed to beadjusted in (fine) 1-knot increments.

Engine-thrust program 512 executes the thrust hold mode (THR) tomaintain the current engine torque. Program 512 may automatically reducethe torque to enforce the applicable power and temperature limits basedon the current rate-of-climb. While the autothrottle is in thearmed-engaged state 612 in THR mode, the pilot may press theautothrottle activation control 204 button to temporarily release theautothrottle into the armed-disengaged state 614, and manually move PCL202 to select a new thrust setting. In armed-disengaged state 614, thePCL will move freely unless it engages to enforce safety limits(overtemp/overspeed/undertorque/underspeed) as per flight-safetyoversight process 504. After adjusting torque, the autothrottle can bere-engaged by pressing the autothrottle activation control 204 buttonagain to maintain the new torque.

In a related embodiment, while in the armed state, the autothrottle alsosets a virtual detent at the maximum continuous thrust (MCT) setting.Additional virtual detents at other thrust settings may likewise beestablished. Such virtual detents make common torque settings easier toselect by the pilot by stopping the PCL when the defined torque settingis reached. When virtual detents are set, the PCL will move freely untilthe detent is reached, at which point the PCL motion is opposed by acounteracting force associated with that virtual detent.

As discussed above, a virtual detent associated with a thrust setting inTHR mode may be automatically moved in response to changing operationalconditions. For instance, the torque limit may be adjusted as a functionof density altitude.

Maximize endurance program 514 implements a dynamic airspeed controlalgorithm for determining and maintaining an efficient operating pointfor aircraft 100 such that the aircraft operates at or near its maximumlift-to-drag (L/D) ratio under the prevailing conditions, such asdescribed in U.S. patent application Ser. No. 17/359,019, the disclosureof which is incorporated by reference herein.

Maximize airspeed program 516 implements a dynamic control algorithm ofautothrottle system 300 for cruise operation that monitors the enginetemperature (e.g., via engine temperature sensor 320) and adjusts thePCL setpoint to produce the maximum speed while maintaining the enginetemperature at or near the applicable max-operating-temperature limit.Program 516 may set and adjust the position of a virtual detent at thedynamic PCL setpoint, allowing the pilot to vary the PCL position asdesired, and to conveniently return the PCL to the temperature-limitedmaximum-speed control point.

Takeoff/go-around program 518 implements takeoff mode (TO), climb mode(CLB), cruise mode (CRZ), and go-around mode (GA), as well as theautomatic transitions between these modes. TO is initiated whileaircraft 100 is on the ground. According to takeoff program 518,autothrottle 300 advances the PCL to maintain maximum continuous torque(MCT). TO is armed by pressing the mode selector 208 button (while onthe ground). Pressing the mode selector 208 button again will disarm TO.

With TO armed, the pilot may initiate the autothrottle takeoff bypressing the takeoff/go around control 206 button on the PCL handle, asdescribed above. This causes the autothrottle 300 to engage and smoothlyincrease power to MCT, where a virtual detent is set. Alternately, thepilot may opt to manually advance the PCL until the autothrottle reachesthe virtual-detent point and engages autothrottle control to maintainMCT. Under such control, the thrust will be maintained at MCT until itis manually or automatically reduced to climb power.

In accordance with takeoff/go-around program 518, TO transitions toclimb mode (CLB) upon meeting the predefined mode-transition criteria.In one implementation, the mode-transition criteria includes apredefined time duration at MCT (e.g., 2-5 minutes). In anotherimplementation, the mode-transition criteria for entering CLB is analtitude gain, which is measurable by an available barometric altimeterin aircraft 100 (e.g., an altitude increase of 400 feet from thealtitude at which the TO was initiated). This approach usesreadily-available altimetry data, rather than relying on a radar-basedaltimeter or other expensive instrumentation, which is not commonlyfound on many small aircraft.

In a related embodiment, the transition criteria for entering CLBincludes manual reduction of PCL 202 by the pilot during TO (e.g., byactuating the autothrottle activation control 204 button to transitionthe autothrottle state to armed-disengaged state 614, reducing power bymanually repositioning PCL 202, and then re-engaging the autothrottle toengaged state 612 by once again actuating activation control 204button).

In climb mode (CLB), the autothrottle maintains MCT, but will reducepower automatically to enforce engine temperature limits. If the takeoffor climb is paused by levelling off (automatically detectable as a lowrate of climb such as less than 200 feet per minute by monitoring theavailable altimeter), the autothrottle will transition to cruise mode(CRZ) and reduce power to the maximum cruise power setpoint, at whichPCL location a virtual detent is set and adjusted as needed). If theclimb is resumed while the autothrottle is still engaged in CRZ, climbpower can be re-selected by the pilot by pressing the activation control204 button to disengage the autothrottle into the armed-disengaged state614 so that the PCL may be manually advanced in order to increase poweruntil the virtual detent associated with MCT engages, therebyre-establishing CLB control.

In cruise mode (CRZ), the autothrottle controls the PCL to producemaximum cruise torque while enforcing engine temperature limits. Avirtual detent is set (and adjusted as needed) at the corresponding PCLposition.

Go-around mode (GA) is similar to TO, except that GA is activated whilethe autothrottle is either in the armed-engaged state 612, orarmed-disengaged state 614, and when aircraft 100 is in the air. Undersuch conditions, GA is activated upon actuation of the takeoff/go aroundcontrol 206 button by the pilot. Once activated, GA functionsessentially in the same manner as TO, i.e., the autothrottle sets thePCL for MCT, sets a virtual detent accordingly, and maintains thissetting until a condition is met to transition to climb mode (CLB) orcruise mode (CRZ).

Additional Notes and Examples

Example 1 is a system for controlling an autothrottle of an aircraftthat includes, a power-control input (PCL) manually movable by a pilotalong a travel path to effect a throttle setting that controls enginepower of the aircraft, the system comprising: an autothrottle controllerincluding processing circuitry, memory, and input/output facilities, theautothrottle controller operative to execute instructions including auser-interface process and an autothrottle control program; anautothrottle actuator mechanically coupled to the PCL and operative toset and dynamically adjust the PCL in response to an output of theautothrottle controller; wherein the autothrottle control program, whenexecuted, causes the autothrottle controller to determine acontrol-target setting and to command the autothrottle actuator to setand dynamically adjust the PCL according to the control-target settingwhen the system is in an engaged state for autothrottle control; andwherein the user-interface process, when executed, causes theautothrottle controller to set and dynamically adjust a virtual detent,the virtual detent being located at a position along the travel path ofthe PCL corresponding to the control-target setting, wherein the virtualdetent is operative, at least when the system is in a disengaged statefor autothrottle control, to indicate the control-target setting to thepilot via a haptic effect that applies a detent force opposing motion ofthe PCL in response to the PCL achieving the position of the virtualdetent.

In Example 2, the subject matter of Example 1 includes, wherein theposition of the virtual detent is dynamically variable by theautothrottle controller in response to adjustment of the control-targetsetting.

In Example 3, the subject matter of Examples 1-2 includes, wherein theuser-interface process causes the autothrottle controller to read pilotinput via a set of at least one input device, and to set an operationalstate from among a disarmed state, and a set of armed states thatinclude the disengaged state and the engaged state, based on the pilotinput; and wherein in the disengaged state, the autothrottle controllerdoes not command the autothrottle actuator to move the PCL to achievethe control-target setting.

In Example 4, the subject matter of Examples 1-3 includes, wherein theautothrottle controller is operative to set a first instance of avirtual detent that applies a first detent force, and to set a secondinstance of a virtual detent that applies a second detent force that isdifferent from the first detent force.

In Example 5, the subject matter of Examples 1-4 includes, wherein theautothrottle controller is operative to transition from the disengagedstate to the engaged state for autothrottle control in response to thePCL being manually positioned at the position of the virtual detent.

In Example 6, the subject matter of Examples 1-5 includes, wherein theautothrottle controller is operative to read pilot input to repositionthe virtual detent from a first position to a second position by manualmovement of the PCL.

In Example 7, the subject matter of Examples 1-6 includes, wherein theautothrottle controller is operative to execute instructions including aflight-safety oversight process that causes the autothrottle controllerto monitor one or more sensors and detect an unsafe operationalcondition, and to dynamically adjust the position of the virtual detentin response to a detected unsafe operational condition.

In Example 8, the subject matter of Examples 1-7 includes, anautothrottle activation input device operatively coupled to theautothrottle controller; an autothrottle mode input device operativelycoupled to the autothrottle controller; and a display device operativelycoupled to the autothrottle controller; wherein the user-interfaceprocess, when executed, causes the autothrottle controller to: respondto actuation of the autothrottle activation input device by togglingbetween the engaged and the disengaged states; respond to actuation ofthe autothrottle mode input device by switching between different onesof a plurality of autothrottle control modes; and display informationindicative of a selected one of the plurality of autothrottle controlmodes on the display device.

In Example 9, the subject matter of Example 8 includes, wherein each ofthe autothrottle activation input device and the autothrottle mode inputdevice comprises a pushbutton.

In Example 10, the subject matter of Examples 8-9 includes, wherein theautothrottle activation input device is situated on the PCL.

In Example 11, the subject matter of Examples 8-10 includes, wherein theautothrottle mode input device is integral with the display device.

In Example 12, the subject matter of Examples 8-11 includes, wherein theplurality of autothrottle control modes includes a takeoff mode, a climbmode, a thrust-hold mode, and a set-speed control mode.

In Example 13, the subject matter of Examples 8-12 includes, wherein atleast one of the plurality of autothrottle control modes, when carriedout by the autothrottle controller, causes the autothrottle controllerto autonomously transition to another one of the autothrottle controlmodes.

In Example 14, the subject matter of Example 13 includes, wherein theautonomous transition from a first one of the plurality of autothrottlecontrol modes to a second one of the plurality of autothrottle controlmodes is performed in response to a determination by the autothrottlecontroller that mode-transition criteria has been met.

In Example 15, the subject matter of Example 14 includes, wherein thefirst one of the plurality of autothrottle control modes is a takeoffmode in which maximum continuous torque (MCT) is maintained, and thesecond one of the plurality of autothrottle control modes is a climbmode in which MCT is maintained, subject to power reduction in responseto an engine temperature limit.

In Example 16, the subject matter of Examples 14-15 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff, go-around, or climb mode in which maximum continuous torque(MCT) is maintained as a control target, and the second one of theplurality of autothrottle control modes is a cruise mode in which acruise torque that is lower than the MCT is maintained as the controltarget.

In Example 17, the subject matter of Examples 14-16 includes, whereinthe mode-transition criteria includes a passage of a predefined timeduration.

In Example 18, the subject matter of Examples 14-17 includes, whereinthe mode-transition criteria includes a predefined altitude gain havingbeen achieved.

In Example 19, the subject matter of Examples 14-18 includes, whereinthe mode-transition criteria includes achieving level flight defined asan altitude gain of less a predefined threshold amount.

Example 20 is a system for controlling an autothrottle of an aircraft,the system comprising: an autothrottle controller including processingcircuitry, memory, and input/output facilities, the autothrottlecontroller operative to execute instructions including a user-interfaceprocess and an autothrottle control program; an autothrottle actuator toset and dynamically adjust a throttle setting that controls engine powerof the aircraft in response to an output of the autothrottle controller;an autothrottle activation input device operatively coupled to theautothrottle controller; an autothrottle mode input device operativelycoupled to the autothrottle controller; and a display device operativelycoupled to the autothrottle controller; wherein the autothrottle controlprogram, when executed, causes the autothrottle controller to determinea control-target setting and to command the autothrottle actuator to setand dynamically adjust the throttle setting according to thecontrol-target setting when the system is in an engaged state forautothrottle control; and wherein the user-interface process, whenexecuted, causes the autothrottle controller to: respond to actuation ofthe autothrottle activation input device by toggling between the engagedand the disengaged states; respond to actuation of the autothrottle modeinput device by switching between different ones of a plurality ofautothrottle control modes; and display information indicative of aselected one of the plurality of autothrottle control modes on thedisplay device.

In Example 21, the subject matter of Example 20 includes, wherein eachof the autothrottle activation input device and the autothrottle modeinput device comprises a pushbutton.

In Example 22, the subject matter of Examples 20-21 includes, whereinthe autothrottle activation input device is situated on the PCL.

In Example 23, the subject matter of Examples 20-22 includes, whereinthe autothrottle mode input device is integral with the display device.

Example 24 is a system for controlling an autothrottle of an aircraft,the system comprising: an autothrottle controller including processingcircuitry, memory, and input/output facilities, the autothrottlecontroller operative to execute instructions including an autothrottlecontrol program; an autothrottle actuator to set and dynamically adjusta throttle setting that controls engine power of the aircraft inresponse to an output of the autothrottle controller; wherein theautothrottle control program, when executed, causes the autothrottlecontroller to: command the autothrottle actuator to set and dynamicallyadjust the throttle setting according to different ones of a pluralityof autothrottle control modes, wherein each of the autothrottle controlmodes defines a corresponding control-target setting; and autonomouslytransition from one of the autothrottle control modes to another one ofthe autothrottle control modes in response to a determination by theautothrottle controller that mode-transition criteria has been met.

In Example 25, the subject matter of Example 24 includes, wherein theplurality of autothrottle control modes includes a takeoff mode, a climbmode, a thrust-hold mode, and a set-speed control mode.

In Example 26, the subject matter of Examples 24-25 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff mode in which maximum continuous torque (MCT) is maintained, andthe second one of the plurality of autothrottle control modes is a climbmode in which MCT is maintained, subject to power reduction in responseto an engine temperature limit.

In Example 27, the subject matter of Examples 24-26 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff, go-around, or climb mode in which maximum continuous torque(MCT) is maintained as a control target, and the second one of theplurality of autothrottle control modes is a cruise mode in which acruise torque that is lower than the MCT is maintained as the controltarget.

In Example 28, the subject matter of Examples 24-27 includes, whereinthe mode-transition criteria includes a passage of a predefined timeduration.

In Example 29, the subject matter of Examples 24-28 includes, whereinthe mode-transition criteria includes a predefined altitude gain havingbeen achieved.

In Example 30, the subject matter of Examples 24-29 includes, whereinthe mode-transition criteria includes achieving level flight defined asan altitude gain of less a predefined threshold amount.

Example 31 is an automated method for controlling an autothrottle of anaircraft that includes, a power-control input (PCL) manually movable bya pilot along a travel path to effect a throttle setting that controlsengine power of the aircraft, the method comprising: determining, by anautothrottle controller, a control-target setting for a throttle of theaircraft; dynamically adjusting the throttle according to thecontrol-target setting, including moving the PCL to achieve thecontrol-target setting when the autothrottle is in an engaged state forautothrottle control; and setting and dynamically adjusting a virtualdetent, the virtual detent being located at a position along a travelpath of the PCL corresponding to the control-target setting, wherein thevirtual detent is operative, at least when the autothrottle is in adisengaged state for autothrottle control, to indicate thecontrol-target setting to the pilot via a haptic effect that applies adetent force opposing motion of the PCL in response to the PCL achievingthe position of the virtual detent.

In Example 32, the subject matter of Example 31 includes, dynamicallyvarying the virtual detent position in response to adjustment of thecontrol-target setting.

In Example 33, the subject matter of Examples 31-32 includes, readingpilot input via a set of at least one input device; and setting anoperational state of the autothrottle from among a disarmed state, and aset of armed states that include the disengaged state and the engagedstate, based on the pilot input, wherein in the disengaged state, thePCL is not moved to achieve the control-target setting.

In Example 34, the subject matter of Examples 31-33 includes, setting afirst instance of a virtual detent that applies a first detent force,and setting a second instance of a virtual detent that applies a seconddetent force that is different from the first detent force.

In Example 35, the subject matter of Examples 31-34 includes,transitioning the autothrottle from the disengaged state to the engagedstate in response to the PCL being manually positioned at the positionof the virtual detent.

In Example 36, the subject matter of Examples 31-35 includes, readingpilot input to reposition the virtual detent from a first position to asecond position by manual movement of the PCL.

In Example 37, the subject matter of Examples 31-36 includes, executinga flight-safety oversight process, including: monitoring one or moresensors and detecting an unsafe operational condition; and dynamicallyadjusting the position of the virtual detent in response to a detectedunsafe operational condition.

In Example 38, the subject matter of Examples 31-37 includes, readinginput from an autothrottle activation input device; reading input froman autothrottle mode input device; responding to actuation of theautothrottle activation input device by toggling between the engaged andthe disengaged states; responding to actuation of the autothrottle modeinput device by switching between different ones of a plurality ofautothrottle control modes; and displaying information indicative of aselected one of the plurality of autothrottle control modes on a displaydevice.

In Example 39, the subject matter of Example 38 includes, wherein theplurality of autothrottle control modes includes a takeoff mode, a climbmode, a thrust-hold mode, and a set-speed control mode.

In Example 40, the subject matter of Examples 38-39 includes, wherein atleast one of the plurality of autothrottle control modes, when carriedout, cause the autothrottle to autonomously transition to another one ofthe autothrottle control modes.

In Example 41, the subject matter of Example 40 includes, wherein theautonomous transition from a first one of the plurality of autothrottlecontrol modes to a second one of the plurality of autothrottle controlmodes is performed in response to determining that mode-transitioncriteria has been met.

In Example 42, the subject matter of Example 41 includes, wherein thefirst one of the plurality of autothrottle control modes is a takeoffmode in which maximum continuous torque (MCT) is maintained, and thesecond one of the plurality of autothrottle control modes is a climbmode in which MCT is maintained, subject to power reduction in responseto an engine temperature limit.

In Example 43, the subject matter of Examples 41-42 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff, go-around, or climb mode in which maximum continuous torque(MCT) is maintained as a control target, and the second one of theplurality of autothrottle control modes is a cruise mode in which acruise torque that is lower than the MCT is maintained as the controltarget.

In Example 44, the subject matter of Examples 41-43 includes, whereinthe mode-transition criteria includes a passage of a predefined timeduration.

In Example 45, the subject matter of Examples 41-44 includes, whereinthe mode-transition criteria includes a predefined altitude gain havingbeen achieved.

In Example 46, the subject matter of Examples 41-45 includes, whereinthe mode-transition criteria includes achieving level flight defined asan altitude gain of less a predefined threshold amount.

Example 47 is a method for controlling an autothrottle of an aircraft,the method comprising: by an autothrottle controller: determining acontrol-target setting for a throttle of the aircraft; dynamicallyadjusting the throttle according to the control-target setting when theautothrottle is in an engaged state for autothrottle control; andreading input from an autothrottle activation input device; readinginput from an autothrottle mode input device; responding to actuation ofthe autothrottle activation input device by toggling between the engagedand the disengaged states; and responding to actuation of theautothrottle mode input device by switching between different ones of aplurality of autothrottle control modes.

Example 48 is a method for controlling an autothrottle of an aircraft,the method comprising: autonomously, dynamically adjusting a throttlesetting according to different ones of a plurality of autothrottlecontrol modes, wherein each of the autothrottle control modes defines acorresponding control-target setting; and autonomously transitioningfrom one of the autothrottle control modes to another one of theautothrottle control modes in response to a determination by theautothrottle controller that mode-transition criteria has been met.

In Example 49, the subject matter of Example 48 includes, wherein theplurality of autothrottle control modes includes a takeoff mode, a climbmode, a thrust-hold mode, and a set-speed control mode.

In Example 50, the subject matter of Examples 48-49 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff mode in which maximum continuous torque (MCT) is maintained, andthe second one of the plurality of autothrottle control modes is a climbmode in which MCT is maintained, subject to power reduction in responseto an engine temperature limit.

In Example 51, the subject matter of Examples 48-50 includes, whereinthe first one of the plurality of autothrottle control modes is atakeoff, go-around, or climb mode in which maximum continuous torque(MCT) is maintained as a control target, and the second one of theplurality of autothrottle control modes is a cruise mode in which acruise torque that is lower than the MCT is maintained as the controltarget.

In Example 52, the subject matter of Examples 48-51 includes, whereinthe mode-transition criteria includes a passage of a predefined timeduration.

In Example 53, the subject matter of Examples 48-52 includes, whereinthe mode-transition criteria includes a predefined altitude gain havingbeen achieved.

In Example 54, the subject matter of Examples 48-53 includes, whereinthe mode-transition criteria includes achieving level flight defined asan altitude gain of less a predefined threshold amount.

Example 55 is at least one machine-readable medium includinginstructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement of any ofExamples 31-54.

Example 56 is an apparatus comprising means to implement of any ofExamples 31-54.

The embodiments above are intended to be illustrative and not limiting.Additional embodiments are within each claim that does not expresslyexclude such subject matter. In addition, although aspects of thepresent invention have been described with reference to particularembodiments, those skilled in the art will recognize that changes may bemade in form and detail without departing from the scope of theinvention, as defined by the claims.

Persons of ordinary skill in the relevant arts will recognize that theinvention may comprise fewer features than illustrated in any individualembodiment described above. The embodiments described herein are notmeant to be an exhaustive presentation of the ways in which the variousfeatures of the invention may be combined. Accordingly, the embodimentsare not mutually exclusive combinations of features; rather, theinvention may comprise a combination of different individual featuresselected from different individual embodiments, as will be understood bypersons of ordinary skill in the art.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims that are included in the documentsare incorporated by reference into the claims of the presentApplication. The claims of any of the documents are, however,incorporated as part of the disclosure herein, unless specificallyexcluded. Any incorporation by reference of documents above is yetfurther limited such that any definitions provided in the documentsapply only to the incorporated subject matter, and not to any of thesubject matter directly present herein.

For purposes of interpreting the claims for the present invention, it isexpressly intended that the provisions of 35 U.S.C. § 112(f) are not tobe invoked unless the specific terms “means for” or “step for” arerecited in a claim.

What is claimed is:
 1. A system for controlling an autothrottle of anaircraft that includes a power-control input (PCL) manually movable by apilot along a travel path to effect a throttle setting that controlsengine power of the aircraft, the system comprising: an autothrottlecontroller including processing circuitry, memory, and input/outputfacilities, the autothrottle controller operative to executeinstructions including a user-interface process and an autothrottlecontrol program; an autothrottle actuator mechanically coupled to thePCL and operative to set and dynamically adjust the PCL in response toan output of the autothrottle controller; an autothrottle activationinput device operatively coupled to the autothrottle controller; anautothrottle mode input device operatively coupled to the autothrottlecontroller; and a display device operatively coupled to the autothrottlecontroller; wherein the autothrottle control program, when executed,causes the autothrottle controller to determine a control-target settingand to command the autothrottle actuator to set and dynamically adjustthe PCL according to the control-target setting when the system is in anengaged state for autothrottle control; wherein the user-interfaceprocess, when executed, causes the autothrottle controller to set anddynamically adjust a virtual detent, the virtual detent being located ata position along the travel path of the PCL corresponding to thecontrol-target setting, wherein the virtual detent is operative, atleast when the system is in a disengaged state for autothrottle control,to indicate the control-target setting to the pilot via a haptic effectthat applies a detent force opposing motion of the PCL in response tothe PCL achieving the position of the virtual detent; and wherein theuser-interface process, when executed, causes the autothrottlecontroller to: respond to actuation of the autothrottle activation inputdevice by toggling between the engaged and the disengaged states;respond to actuation of the autothrottle mode input device by switchingbetween different ones of a plurality of autothrottle control modes; anddisplay information indicative of a selected one of the plurality ofautothrottle control modes on the display device.
 2. The system of claim1, wherein each of the autothrottle activation input device and theautothrottle mode input device comprises a pushbutton.
 3. The system ofclaim 1, wherein the autothrottle activation input device is situated onthe PCL.
 4. The system of claim 1, wherein the autothrottle mode inputdevice is integral with the display device.
 5. The system of claim 1,wherein the plurality of autothrottle control modes includes a takeoffmode, a climb mode, a thrust-hold mode, and a set-speed control mode. 6.The system of claim 1, wherein at least one of the plurality ofautothrottle control modes, when carried out by the autothrottlecontroller, causes the autothrottle controller to autonomouslytransition to another one of the autothrottle control modes.
 7. Thesystem of claim 6, wherein the autonomous transition from a first one ofthe plurality of autothrottle control modes to a second one of theplurality of autothrottle control modes is performed in response to adetermination by the autothrottle controller that mode-transitioncriteria has been met.
 8. The system of claim 7, wherein the first oneof the plurality of autothrottle control modes is a takeoff mode inwhich maximum continuous torque (MCT) is maintained, and the second oneof the plurality of autothrottle control modes is a climb mode in whichMCT is maintained, subject to power reduction in response to an enginetemperature limit.
 9. The system of claim 7, wherein the first one ofthe plurality of autothrottle control modes is a takeoff, go-around, orclimb mode in which maximum continuous torque (MCT) is maintained as acontrol target, and the second one of the plurality of autothrottlecontrol modes is a cruise mode in which a cruise torque that is lowerthan the MCT is maintained as the control target.
 10. The system ofclaim 7, wherein the mode-transition criteria includes a passage of apredefined time duration.
 11. The system of claim 7, wherein themode-transition criteria includes a predefined altitude gain having beenachieved.
 12. The system of claim 7, wherein the mode-transitioncriteria includes achieving level flight defined as an altitude gain ofless a predefined threshold amount.
 13. An automated method forcontrolling an autothrottle of an aircraft that includes a power-controlinput (PCL) manually movable by a pilot along a travel path to effect athrottle setting that controls engine power of the aircraft, the methodcomprising: determining, by an autothrottle controller a control-targetsetting for a throttle of the aircraft; dynamically adjusting thethrottle according to the control-target setting, including moving thePCL to achieve the control-target setting when the autothrottle is in anengaged state for autothrottle control; setting and dynamicallyadjusting a virtual detent, the virtual detent being located at aposition along the travel path of the PCL corresponding to thecontrol-target setting, wherein the virtual detent is operative, atleast when the autothrottle is in a disengaged state for autothrottlecontrol, to indicate the control-target setting to the pilot via ahaptic effect that applies a detent force opposing motion of the PCL inresponse to the PCL achieving the position of the virtual detent;reading input from an autothrottle activation input device; readinginput from an autothrottle mode input device; responding to actuation ofthe autothrottle activation input device by toggling between the engagedand the disengaged states; responding to actuation of the autothrottlemode input device by switching between different ones of a plurality ofautothrottle control modes; and displaying information indicative of aselected one of the plurality of autothrottle control modes on a displaydevice.
 14. The method of claim 13, wherein the plurality ofautothrottle control modes includes a takeoff mode, a climb mode, athrust-hold mode, and a set-speed control mode.
 15. The method of claim13, wherein at least one of the plurality of autothrottle control modes,when carried out, cause the autothrottle to autonomously transition toanother one of the autothrottle control modes.
 16. The method of claim15, wherein the autonomous transition from a first one of the pluralityof autothrottle control modes to a second one of the plurality ofautothrottle control modes is performed in response to determining thatmode-transition criteria has been met.
 17. The method of claim 16,wherein the first one of the plurality of autothrottle control modes isa takeoff mode in which maximum continuous torque (MCT) is maintained,and the second one of the plurality of autothrottle control modes is aclimb mode in which MCT is maintained, subject to power reduction inresponse to an engine temperature limit.
 18. The method of claim 16,wherein the first one of the plurality of autothrottle control modes isa takeoff, go-around, or climb mode in which maximum continuous torque(MCT) is maintained as a control target, and the second one of theplurality of autothrottle control modes is a cruise mode in which acruise torque that is lower than the MCT is maintained as the controltarget.
 19. The method of claim 16, wherein the mode-transition criteriaincludes a passage of a predefined time duration.
 20. The method ofclaim 16, wherein the mode-transition criteria includes one of (i) apredefined altitude gain having been achieved; and (ii) achieving levelflight defined as an altitude gain of less a predefined thresholdamount.